1. Field of the Invention
The present invention relates to the field of telecommunications. More particularly, the present invention relates to establishing broadband Internet protocol (IP) connections over a switched network, capable of guaranteeing desired connection parameters, based on resource reservation protocol (RSVP) signaling.
2. Acronyms
The written description provided herein contains acronyms which refer to various telecommunications services, components and techniques, as well as features relating to the present invention. Although some of these acronyms are known, use of these acronyms is not strictly standardized in the art. For purposes of the written description herein, the acronyms are defined as follows:    Address Resolution Protocol (ARP)    Asynchronous Transfer Mode (ATM)    Constraint-Based Routed Label Distribution Protocol (CR-LDP)    Digital Subscriber Line (DSL)    Domain Naming System (DNS)    Dynamic Host Configuration Protocol (DHCP)    Generalized Multi-Protocol Label Switching (GMPLS)    Internet Protocol (IP)    Internet Service Provider (ISP)    Interworking Function (IWF)    Last-In-First-Out (LIFO)    Local Area Network (LAN)    Local IP Subnet (LIS)    Multiple Address Resolution Server (MARS)    Multi-Protocol Label Switching (MPLS)    Network Service Access Point (NSAP)    Next Hop Resolution Protocol (NHRP)    Next Hop Server (NHS)    Non-Broadcasting Multiple Access (NBMA)    Permanent Virtual Circuit (PVC)    Private Network-to-Network Interface (PNNI)    Resource Reservation Protocol (RSVP)    Quality of Service (QoS)    Request for Comment (RFC)    Switched Virtual Circuit (SVC)    Time Division Multiplex (TDM)    Transmission Control Protocol (TCP)    Universal Resource Locator (URL)    User Datagram Protocol (UDP)    User Network Interface (UNI)    User-to-User Information Element (UU IE)    Virtual Channel Identifier (VCI)    Virtual Path Identifier (VPI)    Virtual Private Network (VPN)    Wide Area Network (WAN)
3. Background and Material Information
With the development of various communications applications for use over packet switched data networks, such as the Internet, demands for predictable bandwidth and delay support are increasing. For example, services including voiceover-Internet and real-time audio, audio-visual and white-board conferencing, require the packets of transmitted data to arrive at a destination terminal with minimal delay and in a presentable order.
Packet switched data networks generally support “best effort” routing of data. The packets of information sent from an originating end-system, such as an Internet subscriber, to a destination end-system, such as an Internet service provider (ISP), are transmitted through a network of interconnected routers using Internet protocol (IP). The IP network essentially divides the transmitted data into packets, each of which travels to the destination end-system through a uniquely determined path among the available routers. The flow of a packet from one router to the next router in the IP network is called a “hop.” The destination end-system ultimately receives the packets and assembles them in the appropriate order to present the transmitted information.
Best effort routing is very flexible in that the data packets travel through any available combination of routers to ultimately reach the destination end-system. When a router becomes unavailable, for example, due to traffic congestion causing its queue threshold to be exceeded, the data packets simply proceed through a different path. A disadvantage of best effort routing is that the speed and quality of the IP traffic is inconsistent due to packets being delayed, lost and received out of order. In typical data transfer scenarios, this disadvantage may be insignificant, especially when additional protocols, such as transmission control protocol/Internet protocol (TCP/IP) and user datagram protocol/Internet protocol (UDP/IP), are implemented to resend and otherwise minimize the effect of lost and delayed data packets. However, many evolving applications depend on consistent and reliable data packet routing, such as those applications involving real-time streaming of audio and/or visual data.
The network criteria, such as bandwidth, needed for the IP network to support these applications are set forth in the quality of service (QoS) parameters. Generally, best effort routing cannot guarantee a particular QoS, especially when a large bandwidth is needed. Differential services may be available in some IP networks. Differential services push aside lower priority traffic to accommodate a predetermined QoS for transmissions of select subscribers, based on a preferred differential level indicator in the data packet headers. However, differential services do not guarantee the desired level of service.
An IP network may also be implemented in conjunction with a non-broadcasting multiple access (NBMA) switched network, such as an asynchronous transfer mode (ATM) network, which is able to set aside communication paths that meet the predefined traffic requirements of the specific applications. For example, an ATM network may set up and tear down a switched virtual circuit (SVC) of a specified bandwidth in response to dynamic communication demands on a per connection basis. The IP network interfaces with a switched network according to various mutually recognized protocols, such as resource reservation protocol (RSVP) and next hop resolution protocol (NHRP). Because the switched network is typically able to isolate or reserve a particular route for the duration of a connection, the required QoS may be established upon connection to the network, accommodating predetermined parameters such as delay, delay jitter and error rate, as well as the demands of the application and the state of the network at the time of connection.
RSVP is a network control protocol that enables QoS connections to be established and maintained by dynamically allocating bandwidth. RSVP is receiver initiated in that the destination end-system initiates the actual reservation of resources or routing elements that enable the connection. When the IP network is implemented over an ATM network, the IP addresses of the routing elements are translated into ATM addresses by a central server or database. The flow may then pass through the switched network by setting up virtual circuits among ATM switches.
NHRP is an address resolution protocol that enables an IP end-system to interface with a switching network, such as an ATM network, and connect with another IP end-system. Use of NHRP extends address resolution between networks across IP subnets. An originating end-system requests a connection through routers in an IP network to a desired destination end-system. A next hop server (NHS) maps the IP address of the destination end-system to its associated ATM address using mapping data and directs the routers to the next hop router in the IP network, until the connection request reaches the destination end-system. Generally, NHRP is not capable of supporting multicast communications.
Although conventional RSVP and NHRP generally enable IP connections over switched networks, they are relatively cumbersome to implement. Both protocols require accessing a central mapping server or database, such as an address resolution protocol (ARP) server or an NBMA-IP server, to associate IP addresses with the corresponding NBMA switched network addresses, and to otherwise control the routing. Each device must register its IP address and NBMA address in the server, which resolves the IP addresses to the registered ATM addresses in response to connection requests. Furthermore, RSVP and NHRP do not accommodate simultaneous, point-to-multipoint (i.e., multicast) transmissions. Also, RSVP has limited scalability due to extension state information and constant refreshment, and many conventional end-systems are not RSVP capable.
The present invention overcomes the problems associated with the prior art, as described below.